Range extenders are not worth the money, they cannot technically improve a WLAN, the concept of a range extender is totally outdated. The best solution for weak WiFi reception is a so-called mesh WiFi system, which consists of several WiFi routers that build a stable WiFi network between them. The ISP's WLAN is disabled, the first mesh router is connected to the ISP's router and other mesh routers are then connected to the first mesh router. This is not difficult to set up. The best solution would be from Xiaomi, the AX3000 system consists of 2 identical mesh routers, the whole system could also be expanded to a maximum of 10 routers. This gives you a stable WLAN, which is also fast and works without any problems.

Xiaomi AX3000